The present invention relates in general to bulk material containers, and more particularly to a bulk material container having a filter vent.
Heretofore storage tanks and containers included filter vents to provide ventilation for permitting fumes to escape and also to prevent foreign matter from obtaining access to the material stored in the tank or container. In such vents, a wire mesh served as the filter. Vents heretofore included a paper filter to permit the entrance or exit of air into or from the container, while restraining the backsplashing of liquid stored in the container through the filter.
Other containers heretofore had vents with a felt filter and screen to provide a breather vent for the material stored in the container. The vent filtered the air entering the container, prevented backsplashing of the material stored in the container and provided breather vent for the intake of air into the container.
In the U.S. Pat. No. 1,921,943, to Rice et al., issued on Aug. 8, 1933, for Screened Vent Cap, there is disclosed a container with a vent pipe. The vent pipe comprises a wire mesh to permit fumes to escape from the container while preventing foreign objects from gaining access to the interior of the container. The U.S. Pat. No. 1,815,920, to Lake, issued on July 28, 1931, for Vent Protector, discloses a container with a vent pipe. The vent pipe comprises a wire mesh screen. The wire mesh screen prevents foreign objects from entering the container, while permitting the container to be in communication with the atmosphere.
The U.S. Pat. No. 2,371,296, to Hopwood, issued on Mar. 13, 1945, for Means For Venting Milk Cans, discloses a container with a vent. The vent comprises a paper filter. The paper filter prevents backsplashing of the material in the container and prevents foreign objects from entering the container. The venting of the container permits the exit of pressure generated in the container and the flow of air into the container to preclude the building up of vacuums in the container.
In the U.S. Pat. No. 1,675,503, to McCallum, issued on July 3, 1928, for Ventilation Attachment For Milk Can Covers, there is disclosed a container with a ventilator. The ventilator comprises a screen of woven wire or perforated sheet metal. The screen provides means for ventilating the container while presenting foreign objects from entering the container. The U.S. Pat. No. 2,603,308, to McCall, issued on July 15, 1952, for Air Filter and Breather For Fluid Fuel Containers, discloses a container with an air filter. The air filter comprises a felt filter and a screen. The air filter serves as a breather and also keeps foreign objects out of the container. Additionally, the air filter prevents backsplashing from the material stored in the container. A central passage is disposed below the air filter.
Heretofore, the filters in breather vents were employed to breathe and to reduce backsplash, but were not employed to protect a bulk material container against rapid increases in vacuum or rapid increases in pressure emanating from the bulk material within the container.